Generally, BLDC motors use semiconductor drive circuits in DC motors such that commutators, brushes, etc. are not needed. Namely, BLDC motors are able to control current using semiconductors, and include an armature performing a stator function, a permanent magnet performing a rotor function, and a position detecting portion performing a brush and commutator function.
The BLDC motor structured as in the above is controlled by detecting the position of the rotor then applying current to a stator according to this position such that motor rotation is controlled. The position detecting portion is provided to detect the position of the rotor and uses either a Hall method using a Hall element, an optical method, a high frequency induction method, a high frequency oscillation method, a reed switch method, or a magnetoresistive element method to detect the position of the rotor.
However, when using a BLDC motor in a compressor, high temperatures and high pressures caused by coolant compression can reduce the reliability of a sensor, and wiring of the position detecting sensor inside the BLDC motor complicates the manufacturing process and increases the size of the motor.